Using a retrospective review, determine the agreement of central corneal thickness (CCT) measurements taken by the CASIA SS-1000 Anterior Segment Ocular Coherence Tomography (ASOCT; Tomey, Nagoya, Japan) with those taken by ultrasound pachymetry (USP), the current clinical gold-standard.

Methods

Patients who had undergone ASOCT imaging using the ‘Corneal Map Mode were reviewed. Participants were included if they had CCT measured by USP on the same date as ASOCT imaging. Patients were excluded if they had anterior segment abnormalities or media opacities that affected the cornea or measurements. If both eyes were eligible, one eye was randomly selected. Eyes were classified into 5 groups: refractive error, keratoconus (KCN)/bullous keratopathy (BK), corneal dystrophy, other corneal diseases, and non-corneal ocular diseases. Agreement was evaluated by the mean difference between ASOCT and USP and limits of agreement.

The CASIA SS-1000 is similar to other ASOCT machines in that it gives a CCT reading lower than the USP, the current gold standard. KCN eyes tend to have larger differences in CCT measurement between ASOCT and USP. This difference may indicate that one modality of CCT measurement is more appropriate in KCN eyes.